I saw the answer to the I'm finished == I'm ready entry but it seems to me that the answers miss the point. What my question is, and probably the user before me also wanted an answer to is, if I'm ready can be used in the meaning of I have just completed something. It is clear that to be ready means you are prepared to start a next course of action, but is it good English or at least does it sound natural if I use it at the end of an activity implicating that I am over it now. (using the phrase I' ready in the meaning of I have just finished something.) Like when you have just made 40 burpees and you sigh: I'm ready.
Or for example you are doing your morning exercise and your brother wants to go somewhere with you and to his suggestion you answer: "Ok, we can go when I am ready."